﻿// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
// Copyright (c) 2011, Dr. Masroor Ehsan
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of the author nor the
//       names of its contributors may be used to endorse or promote products
//       derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 
// $Author: masroore@gmail.com $
// $Id: Entity.cs 37 2011-10-21 15:00:21Z masroore@gmail.com $
// $Rev: 37 $
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

using System;

namespace MaxTrader.BusinessObjects
{
    public abstract class Entity<T>
    {
        public virtual T Id { get; protected set; }

        public override bool Equals(object obj)
        {
            return Equals(obj as Entity<T>);
        }

        private static bool IsTransient(Entity<T> obj)
        {
            return (obj != null) && Equals(obj.Id, default(T));
        }

        private Type GetUnproxiedType()
        {
            return GetType();
        }

        public virtual bool Equals(Entity<T> other)
        {
            if (other == null)
            {
                return false;
            }

            if (ReferenceEquals(this, other))
            {
                return true;
            }

            if ((!IsTransient(this)) && (!IsTransient(other)) && Equals(Id, other.Id))
            {
                var thisType = GetUnproxiedType();
                var otherType = other.GetUnproxiedType();
                return thisType.IsAssignableFrom(otherType) || otherType.IsAssignableFrom(thisType);
            }

            return false;
        }

        public override int GetHashCode()
        {
            if (Equals(Id, default(T)))
            {
                return base.GetHashCode();
            }

            return Id.GetHashCode();
        }
    }

    public abstract class Entity : Entity<int>
    {
    }
}